Currently high-end mobile devices such as smartphones and tablet computers provide abundant storage for storing applications, media files and documents, etc., by providing the respective devices with high-capacity memories or by providing the respective devices with a connection to cloud-based storages. Further, users often use cameras included in the mobile devices to take photos and/or videos, and also store a large volume of such photos and/or videos in their mobile devices and/or the cloud-based storages. Also, the users often download various files such as, for example, media files and documents from other devices such as, for example, servers or other mobile devices, and store the downloaded files in their mobile devices and/or the cloud-based storages.
Some users manage their content files using a conventional file managing scheme such as, for example, folder classification and/or keyword-based tagging. However, such a conventional file managing scheme requires extra efforts of the users, in that the users should store data in suitable folders and/or add suitable keywords and tags in advance. Furthermore, even with the file managing scheme, it is still difficult for the users to easily find and select the desired files from storage in which a large number of files are stored.